Mgvalleys: fix riverbeds below sea level

Stop riverbeds from forming plateaus under sea. Minor corrections to
random lava/water placement.

diff --git a/src/mapgen_valleys.cpp b/src/mapgen_valleys.cpp
index f003ae63c1d89cf8759847be2d9a356c98a8b74e..ceb2c774d988f693ac1f14260b7c5186a012f49a 100644 (file)
--- a/src/mapgen_valleys.cpp
+++ b/src/mapgen_valleys.cpp
@@ -99,8 +99,8 @@ MapgenValleys::MapgenValleys(int mapgenid, MapgenParams *params, EmergeManager *
        this->water_features_lim = rangelim(sp->water_features, 0, 10);
 
        // a small chance of overflows if the settings are very high
-       this->cave_water_max_height = water_level + MYMAX(0, water_features_lim - 6) * 50;
-       this->lava_max_height       = water_level + MYMAX(0, lava_features_lim - 6) * 50;
+       this->cave_water_max_height = water_level + MYMAX(0, water_features_lim - 4) * 50;
+       this->lava_max_height       = water_level + MYMAX(0, lava_features_lim - 4) * 50;
 
        tcave_cache = new float[csize.Y + 2];
 
@@ -482,7 +482,8 @@ float MapgenValleys::terrainLevelFromNoise(TerrainNoise *tn)
 
                // base - depth : height of the bottom of the river
                // water_level - 6 : don't make rivers below 6 nodes under the surface
-               mount = rangelim(base - depth, (float) (water_level - 6), mount);
+               // There is no logical equivalent to this using rangelim.
+               mount = MYMIN(MYMAX(base - depth, (float) (water_level - 6)), mount);
 
                // Slope has no influence on rivers.
                *tn->slope = 0.f;
@@ -846,8 +847,8 @@ void MapgenValleys::generateCaves(s16 max_stone_y)
 
        // Reduce the odds of overflows even further.
        if (node_max.Y > water_level) {
-               lava_chance /= 5;
-               water_chance /= 5;
+               lava_chance /= 3;
+               water_chance /= 3;
        }
 
        u32 index_2d = 0;